What was found
RIGHT MAIN LANDING GEAR FAILED TO UNLOCK WHEN EXTENDED. PILOT TRIED NUMEROUS TIMES TO GET GEAR TO EXTEND INCLUDING MANUALLY PUMPING. HE ELECTED TO LAND GEAR UP. DURING INCIDENT INVESTIGATION, FOUND THE UPLOCK LEVER TO CONTROL LINK PIN MISSING. MAINTENANCE DID NOT COTTER PIN THE PIN. THE OPPOSITE PIN WAS ALSO MISSING COTTER PIN, BUT WAS STILL IN PLACE.